Merge pull request #14579 from nextcloud/copilot/enhance-pr-template-checklist

chore: add contributor checklist to PR template

Author: miaulalala

.github/pull_request_template.md

@@ -9,3 +9,10 @@ Please add a screenshot of your changed or added page(s).
 This helps reviewers to quickly see how the resulting
 lists, code blocks, headers and links look.
 -->
+
+### ✅ Checklist
+
+- [ ] I have built the documentation locally and reviewed the output
+- [ ] Screenshots are included for visual changes
+- [ ] I have not moved or renamed pages (or added a redirect if I did)
+- [ ] I have run `codespell` or similar and addressed any spelling issues